Fabrication of vertical transport fin field effect transistors with a self-aligned separator and an isolation region with an air gap

ABSTRACT

A method of forming a vertical transport fin field effect transistor with self-aligned dielectric separators, including, forming a bottom source/drain region on a substrate, forming at least two vertical fins on the bottom source/drain region, forming a protective spacer on the at least two vertical fins, forming a sacrificial liner on the protective spacer, forming an isolation channel in the bottom source/drain region and substrate between two of the at least two vertical fins, forming an insulating plug in the isolation channel, wherein the insulating plug has a pinch-off void within the isolation channel, and forming the dielectric separator on the insulating plug.

BACKGROUND Technical Field

The present invention generally relates to utilizing two adjacentvertical fins to align a deep isolation region without having toincrease the distance between the vertical fins, and more particularlyto using a protective spacer and sacrificial liner on the vertical finsto align the deep isolation region and an insulating plug.

Description of the Related Art

A Field Effect Transistor (FET) typically has a source, a channel, and adrain, where current flows from the source to the drain, and a gate thatcontrols the flow of current through the channel. Field EffectTransistors (FETs) can have a variety of different structures, forexample, FETs have been fabricated with the source, channel, and drainformed in the substrate material itself, where the current flowshorizontally (i.e., in the plane of the substrate), and FinFETs havebeen formed with the channel extending outward from the substrate, butwhere the current also flows horizontally from a source to a drain. Thechannel for the FinFET can be an upright slab of thin approximatelyrectangular Si, commonly referred to as the fin with a gate on the fin,as compared to a metal-oxide-semiconductor field effect transistor(MOSFET) with a gate parallel with the plane of the substrate.

Depending on the doping of the source and drain, an n-type FET (nFET) ora p-type FET (pFET) can be formed. An nFET and a pFET can be coupled toform a complementary metal oxide semiconductor (CMOS) device, where ap-channel MOSFET and n-channel MOSFET are coupled together.

With ever decreasing device dimensions, forming the individualcomponents and electrical contacts become more difficult. An approach istherefore needed that retains the positive aspects of traditional FETstructures, while overcoming the scaling issues created by formingsmaller device components, including channel lengths and gate dielectricthicknesses.

SUMMARY

In accordance with an embodiment of the present invention, a method offorming a vertical transport fin field effect transistor withself-aligned dielectric separators is provided. The method includesforming a bottom source/drain region on a substrate, and forming atleast two vertical fins on the bottom source/drain region. The methodfurther includes forming a protective spacer on the at least twovertical fins, and forming a sacrificial liner on the protective spacer.The method further includes forming an isolation channel in the bottomsource/drain region and substrate between two of the at least twovertical fins, and forming an insulating plug in the isolation channel,wherein the insulating plug has a pinch-off void within the isolationchannel, and forming the dielectric separator on the insulating plug.

In accordance with another embodiment of the present invention, a methodof forming a vertical transport fin field effect transistor withself-aligned dielectric separators is provided. The method includesforming at least two vertical fins on a substrate, and forming aprotective spacer on the at least two vertical fins. The method furtherincludes forming a sacrificial liner on the protective spacer, andforming an isolation channel in the substrate between two of the atleast two vertical fins. The method further includes forming aninsulating plug in the isolation channel, wherein the insulating plughas a pinch-off void within the isolation channel, and the insulatingplug and the protective spacer are the same material. The method furtherincludes forming the dielectric separator on the insulating plug, andremoving a portion of the insulating plug on the dielectric separator,and a portion of the protective spacer on the two of the at least twovertical fins.

In accordance with yet another embodiment of the present invention, avertical transport fin field effect transistor with self-aligneddielectric separators is provided. The vertical transport fin fieldeffect transistor includes a bottom source/drain region on a substrate,and at least two vertical fins on the bottom source/drain region. Thevertical transport fin field effect transistor further includes anisolation channel in the bottom source/drain region and substratebetween two of the at least two vertical fins, and an insulating plug inthe isolation channel, wherein the insulating plug has a pinch-off voidwithin the isolation channel. The vertical transport fin field effecttransistor further includes the dielectric separator on the insulatingplug.

These and other features and advantages will become apparent from thefollowing detailed description of illustrative embodiments thereof,which is to be read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description will provide details of preferred embodimentswith reference to the following figures wherein:

FIG. 1 is a cross-sectional side view showing a bottom source/drainregion of a substrate, a fin layer on the bottom source/drain region,and fin template layer on the fin layer, in accordance with anembodiment of the present invention;

FIG. 2 is a cross-sectional side view showing fin templates on aplurality of vertical fins, in accordance with an embodiment of thepresent invention;

FIG. 3 is a cross-sectional side view showing a protective spacer on thefin templates and vertical fins, in accordance with an embodiment of thepresent invention;

FIG. 4 is a cross-sectional side view showing a sacrificial liner on theprotective spacer, in accordance with an embodiment of the presentinvention;

FIG. 5 is a cross-sectional side view showing exposed horizontalsurfaces of the protective spacer, in accordance with an embodiment ofthe present invention;

FIG. 6 is a cross-sectional side view showing a trench in a fill layerexposing the protective spacer, in accordance with an embodiment of thepresent invention;

FIG. 7 is a cross-sectional side view showing an opening formed in theprotective spacer exposing the underlying substrate, in accordance withan embodiment of the present invention;

FIG. 8 is a cross-sectional side view showing removal of the exposedsacrificial liner, and an isolation channel formed in the bottomsource/drain layer and substrate, in accordance with an embodiment ofthe present invention;

FIG. 9 is a cross-sectional side view showing an insulating plug andpinch-off void in the isolation channel to form a deep isolation region,in accordance with an embodiment of the present invention;

FIG. 10 is a cross-sectional side view showing a self-aligned dielectricseparator on the insulating plug, in accordance with an embodiment ofthe present invention;

FIG. 11 is a cross-sectional side view showing an exposed sacrificialliner after removing the fill layer, in accordance with an embodiment ofthe present invention;

FIG. 12 is a cross-sectional side view showing exposed vertical fins andfin templates after removing the protective spacer, in accordance withan embodiment of the present invention;

FIG. 13 is a cross-sectional side view showing gate structures formed onthe vertical fins and a bottom spacer, in accordance with an embodimentof the present invention;

FIG. 14 is a cross-sectional side view showing a top spacer on the gatestructures and top source/drains on the vertical fins, in accordancewith an embodiment of the present invention;

FIG. 15 is a cross-sectional side view showing shared gate structuresformed on the vertical fins and a bottom spacer without a dielectricseparator on the insulating plug, in accordance with an embodiment ofthe present invention; and

FIG. 16 is a cross-sectional side view showing a top spacer on the gatestructures without a dielectric separator, and top source/drains on thevertical fins, in accordance with an embodiment of the presentinvention.

DETAILED DESCRIPTION

Embodiments of the present invention relate generally to utilizing twoadjacent vertical fins to align a deep isolation region without havingto increase the distance between the vertical fins or performing afin-cut (i.e., within one fin spacing). The vertical fins can be formedwith a consistent fin pitch through, for example, a sidewall imagetransfer (SIT) process, and the deep isolation region properly alignedbetween two vertical fins without additional processing steps, fin-cutsteps, or mask alignments. The width of the deep isolation region can besufficiently maintained, and increased parasitic capacitances can bereduced or avoided.

Embodiments of the present invention also relate to using a protectivespacer and sacrificial liner on the vertical fins to align the deepisolation region and an insulating plug to physically separate andelectrically isolate adjacent vertical fin field effect devices (VTFinFETs).

Embodiments of the present invention also relate to forming a void spacein the insulating plug by pinching off the opening of the isolationchannel using a non-conformal deposition process. The pinch-off void inthe isolation channel can provide a lower dielectric value for the deepisolation region.

Embodiments of the present invention also relate to reducing theparasitic capacitance by forming an air gap (also referred to as a voidspace) in the deep isolation region by utilizing a deposition processthat occludes the proximal opening of the isolation channel before aninsulating, dielectric material can fully fill the isolation channel.Conformal depositions are, therefore, avoided to prevent alayer-by-layer build up that would fill the isolation channel.

Exemplary applications/uses to which the present invention can beapplied include, but are not limited to: logic devices (e.g., gates,flip-flops) and memory devices (e.g., SRAM, DRAM).

It is to be understood that aspects of the present invention will bedescribed in terms of a given illustrative architecture; however, otherarchitectures, structures, substrate materials and process features andsteps can be varied within the scope of aspects of the presentinvention.

It should be noted that certain features may not be shown in all figuresfor the sake of clarity. This is not intended to be interpreted as alimitation of any particular embodiment, or illustration, or scope ofthe claims.

Reference to source/drain projections, layers, regions, etc., isintended to indicate that the particular device feature can beimplemented as a source or a drain except as expressly indicatedotherwise. As further described herein, the source and drain also can bedifferent due to fabrication with different materials providingdifferent electrical properties. In addition, the role of source anddrain for an active device can in some instances be reversed, so apreviously indicated drain may instead be a source and vice versa.Reference to a source/drain is, therefore, intended to encompass thebroadest reasonable scope of the term.

Referring now to the drawings in which like numerals represent the sameor similar elements and initially to FIG. 1, a cross-sectional side viewof a bottom source/drain region of a substrate, a fin layer on thebottom source/drain region, and fin template layer on the fin layer, inaccordance with an embodiment of the present invention, is shown.

In one or more embodiments, a substrate 110 can be a semiconductor or aninsulator with an active surface semiconductor layer. The substrate caninclude a carrier layer that provides mechanical support for otherlayers of the substrate. The substrate can include crystalline,semi-crystalline, microcrystalline, or amorphous regions. The substratecan be essentially (i.e., except for contaminants) a single element(e.g., silicon), primarily (i.e., with doping) of a single element, forexample, silicon (Si) or germanium (Ge), and/or the substrate caninclude a compound, for example, Al₂O₃, SiO₂, GaAs, SiC, Si:C, or SiGe.The substrate can also have multiple material layers, for example, asemiconductor-on-insulator substrate (SeOI), such as asilicon-on-insulator substrate (SOI), germanium-on-insulator substrate(GeOI), or silicon-germanium-on-insulator substrate (SGOI). Thesubstrate can also have other layers forming the substrate, includinghigh-k oxides and/or nitrides. Other semiconductor devices and features,such as shallow trench isolation (STI) regions, may already be formed onthe substrate.

In one or more embodiments, a bottom source/drain region 115 can beformed at the surface of the substrate, where the bottom source/drainregion 115 can be formed on the surface of the substrate or implantedinto a surface region of the substrate. The bottom source/drain region115 can be epitaxially grown on the surface of the substrate 110, wherethe substrate surface can have a predetermined crystal face (e.g.,(100)). The bottom source/drain region 115 can be a doped layer thatincludes dopant species suitable to form a p-type bottom source/drainregion 115 (e.g., boron, gallium, and indium), or dopant speciessuitable to form an n-type bottom source/drain region 115 (e.g.,phosphorus, arsenic, and antimony).

In one or more embodiments, a fin layer 120 can be formed on the bottomsource/drain region 115. The fin layer 120 can be formed by epitaxialgrowth on the bottom source/drain region 115. In one or moreembodiments, the fin layer 120 can be single crystal silicon (Si) orsingle crystal silicon-germanium (SiGe) with the same crystalorientation as the bottom source/drain region 115 on which the fin layer120 is grown. In various embodiments, the fin layer 120 can be asemiconductor material, which can be an intrinsic semiconductor material(e.g., silicon (Si)).

In one or more embodiments, a fin template layer 130 can be formed onthe fin layer 120, where the fin template layer 130 can be a hardmask.The fin template layer 130 can be blanket deposited, for example, bychemical vapor deposition (CVD) or plasma enhanced chemical vapordeposition (PECVD) on the exposed surface of the fin layer 120.

FIG. 2 is a cross-sectional side view showing fin templates on aplurality of vertical fins, in accordance with an embodiment of thepresent invention.

In one or more embodiments, fin templates 121 can be formed on the finlayer 120. The fin template layer 130 can be patterned by such processesto form one or more fin templates 131, where the fin templates 131 canbe used to mask portions of the underlying fin layer 120. In variousembodiments, portions of the fin layer 120 exposed between fin templates131 can be removed, for example, by a directional selective etch, suchas a reactive ion etch (RIE), to form one or more vertical fins 121.

In various embodiments, a plurality of vertical fins 121 can be formedby a sidewall image transfer (SIT) process, self-aligned doublepatterning (SADP) process, or self-aligned quadruple patterning (SAQP)process, to provide a tight pitch between vertical fins 121. In variousembodiments, a direct print can be used to provide the fin templates 131from the fin template layer 130. Immersion Lithography can direct printdown to about 78 nm pitch. Extreme ultraviolet lithography (also knownas EUV or EUVL), considered a next-generation lithography technologyusing an extreme ultraviolet (EUV) wavelength, can direct print down toa pitch smaller than 50 nm. Self-aligned double patterning (SADP) canachieve down to about 40 nm to 60 nm fin pitch. Self-aligned quadruplepatterning (SAQP) may be used to go down to below 40 nm fin pitch. Thevertical fins 121 can have a uniform spacing, as determined by thefabrication process. In various embodiments, two vertical fins can beseparated by a fin pitch in the range of about 15 nm to about 50 nm, orabout 15 nm to about 35 nm.

FIG. 3 is a cross-sectional side view showing a protective spacer on thefin templates and vertical fins, in accordance with an embodiment of thepresent invention.

In one or more embodiments, a protective spacer 140 can be formed on thefin templates 131, vertical fins 121, and substrate 110. The protectivespacer 140 can be formed by a conformal deposition (e.g., by atomiclayer deposition (ALD), plasma enhanced atomic layer deposition (PEALD))to control the thickness of the protective spacer 140. The protectivespacer 140 can be silicon oxide (SiO), a silicon nitride (SiN), asilicon oxynitride (SiON), a silicon carbonitride (SiCN), a siliconboronitride (SiBN), a silicon borocarbide (SiBC), a silicon borocarbonitride (SiBCN), or a combination thereof.

In various embodiments, the protective spacer 140 can have a thicknessin the range of about 1 nm to about 5 nm.

FIG. 4 is a cross-sectional side view showing a sacrificial liner on theprotective spacer, in accordance with an embodiment of the presentinvention.

In one or more embodiments, a sacrificial liner 150 can be formed on theprotective spacer 140, where the sacrificial liner 150 can be formed bya conformal deposition. The sacrificial liner 150 can be can beamorphous silicon (a-Si), poly-silicon (p-Si), amorphous carbon (a-C),silicon-germanium (SiGe), an organic planarization layer (OPL), siliconoxide (SiO), silicon nitride (SiN), or suitable combinations thereof.The sacrificial liner 150 can be selectively etchable over theprotective spacer 140.

In various embodiments, the sacrificial liner 150 can have a thicknessin the range of about 1 nm to about 10 nm. The sacrificial liner 150 canbe used to control the width of an isolation channel and a subsequentlyformed dielectric separator. The sacrificial liner 150 thickness andprotective spacer 140 thickness can determine the spacing between adielectric separator and vertical fin sidewall for subsequent formationof gate structures on portions of adjacent FinFETs.

FIG. 5 is a cross-sectional side view showing exposed horizontalsurfaces of the protective spacer, in accordance with an embodiment ofthe present invention.

In one or more embodiments, the sacrificial liner 150 can be removedfrom the horizontal surfaces to expose the protective spacer 140. Adirectional etch can be used to remove the sacrificial liner materialfrom surfaces approximately perpendicular to the ion beam, while thesacrificial liner 150 remains on the vertical surfaces. The protectivespacer 140 can act as an etch stop to protect the underlying bottomsource/drain region 115.

FIG. 6 is a cross-sectional side view showing a trench in a fill layerexposing the protective spacer, in accordance with an embodiment of thepresent invention.

In one or more embodiments, a fill layer 160 can be formed on thesacrificial liner 150 and protective spacer 140, where the fill layer160 can fill in the spaces between the vertical fins 121 and fintemplates 131. The fill layer 160 can be blanket deposited and a CMPused to provide a flat, uniform surface. The fill layer 160 can be aflowable oxide or suitable polymeric material.

In one or more embodiments, a portion of the fill layer 160 can beremoved from between two vertical fins 121 to form a trench 170 thatexposes the underlying protective spacer 140. The fill layer 160 can beremoved by patterning and developing a lithography mask and using aselective, directional etch to remove the exposed fill layer material.The sacrificial liner 150 can be exposed on the vertical side walls ofthe trench 170, and the protective spacer 140 can be exposed at thebottom of the trench 170 and on the horizontal surfaces of the fintemplates 131. The thickness of the sacrificial liner can define adistance between the upper edge and sidewall of the trench 170 to theside walls of the protective spacer 140.

FIG. 7 is a cross-sectional side view showing an opening formed in theprotective spacer exposing the underlying substrate, in accordance withan embodiment of the present invention.

In one or more embodiments, a directional etch can be used to remove theexposed portion of the protective spacer 140 on the fin templates 131and form an opening in the protective spacer 140 at the bottom of thetrench 170.

FIG. 8 is a cross-sectional side view showing removal of the exposedsacrificial liner, and an isolation channel formed in the bottomsource/drain layer and substrate, in accordance with an embodiment ofthe present invention.

In one or more embodiments, an isolation channel 180 can be formed inthe bottom source/drain region 115 and substrate 110 using a selective,directional etch. The isolation channel 180 can separate the bottomsource/drain region 115 into two sections, and extend into the substrate110.

FIG. 9 is a cross-sectional side view showing an insulating plug andpinch-off void in the isolation channel to form a deep isolation region,in accordance with an embodiment of the present invention.

In one or more embodiments, an insulating plug 190 can be formed in theisolation channel 180 and on the protective spacers 140. The insulatingplug 190 can be formed by chemical vapor deposition (CVD) or plasmaenhanced chemical vapor deposition (PECVD) to occlude the opening in theisolation channel 180 at the top surface of the bottom source/drainregion 115 to form a pinch-off void 195. A CVD or PECVD deposition canpinch-off the opening before the entire isolation channel 180 is filledwith an insulating, dielectric material. The insulating plug 190 caninclude a layer of the insulating, dielectric material on the exposedvertical surfaces and top surfaces of the fin templates 131. Thepinch-off void 195 can contain air that can form an air gap betweencomponents of adjacent fin field effect transistors (FinFETs). Theinsulating plug 190 and pinch-off void 195 can provide a lowerdielectric constant between the adjacent FinFETs to reduce parasiticcapacitances.

In one or more embodiments, the insulating plug 190 can be silicon oxide(SiO). The insulating plug 190 can be the same material as theprotective spacer 140 to allow both a portion of the insulating plug 190and a portion of the protective spacer 140 to be removed at the sametime.

In one or more embodiments, a dielectric separator 200 can be formed onthe insulating plug 195, where the dielectric separator 200 canphysically and electrically separate adjacent vertical fins 121. Thedielectric separator 200 can be silicon oxide (SiO), a low-k dielectric,or a combination thereof. The dielectric separator 200 can electricallyinsulate adjacent gate structures on the vertical fins 121. Thedielectric separator can have a width in the range of about 5 nm toabout 40 nm, or in the range of about 10 nm to about 30 nm.

FIG. 11 is a cross-sectional side view showing an exposed sacrificialliner after removing the fill layer, in accordance with an embodiment ofthe present invention.

In one or more embodiments, the remaining fill layer 160 can be removedfrom the vertical fins 121, where the fill layer 160 can be removedusing a selective etch.

FIG. 12 is a cross-sectional side view showing exposed vertical fins andfin templates after removing the protective spacer, in accordance withan embodiment of the present invention.

In one or more embodiments, an upper portion of the insulating plug 190on the side walls of the dielectric separator 200 and protective spacer140 can be removed to expose the side walls of the dielectric separator200. The insulating plug 190 and protective spacer 140 can be removed atthe same time using a selective etch, where the insulating plug 190 andprotective spacer 140 are the same material (e.g., SiO). An insulatingcap 197 can remain between the bottom surface of the dielectricseparator 200 and the top surface of the bottom source/drain region 115,where the dielectric separator 200 masks the underlying portion of theinsulating plug 190. The protective spacer 140 can be removed from theexposed surfaces of the vertical fins 121 and fin templates 131 using anisotropic etch.

FIG. 13 is a cross-sectional side view showing gate structures formed onthe vertical fins and a bottom spacer, in accordance with an embodimentof the present invention.

In one or more embodiments, a bottom spacer 210 can be formed on theexposed surfaces of the bottom source/drain region 115. The bottomspacer 210 can be an insulating, dielectric material that physically andelectrically separates the bottom source/drain region 115 from asubsequently formed gate structure. The bottom spacer 210 can be siliconnitride (SiN).

In one or more embodiments, gate structures can be formed on thevertical fins 121 and a bottom spacer 210. The gate structures caninclude gate dielectric layers 220 and a conductive gate electrode 230including a conductive gate fill and optionally a work function layer.The gate dielectric layer 220 can be formed on the exposed surfaces ofthe vertical fins 121, fin templates 131, and bottom spacer 210. A workfunction layer can be formed on the gate dielectric layer 220. Aconductive gate fill can be formed on the gate dielectric layer 220 oroptional work function layer. The conductive gate fill, work functionlayer, and gate dielectric layer 220 can be conformally deposited andetched back to form the gate structure on a portion of the vertical fins121.

The gate dielectric layer 220 can be silicon oxide (SiO), siliconnitride (SiN), a high-k dielectric material, or a combination thereof.The work function layer can be a suitable metal nitride or metalcarbide, or a stack of suitable layers.

A gate structure can be formed between the dielectric separator 200 andthe adjacent vertical fins 121, where the gate dielectric layer 220 andwork function layer can be conformally deposited on the exposedsurfaces.

FIG. 14 is a cross-sectional side view showing a top spacer on the gatestructures and top source/drains on the vertical fins, in accordancewith an embodiment of the present invention.

In one or more embodiments, a top spacer 240 can be formed on the gatestructures and the vertical fins 121. The top spacer 240 can bedirectionally deposited and etched back to have a predeterminedthickness. The top spacer 240 can be an insulating dielectric material,for example, silicon oxide (SiO).

In one or more embodiments, an interlayer dielectric (ILD) layer 250 canbe formed on the top spacer layer 240 and fin templates 131. A CMP canbe used to reduce the height of the ILD layer 250 and expose the topsurface of the fin templates 131. The fin templates 131 can be removedby a selective etch to expose the top surfaces of the vertical fins 121.

In one or more embodiments, top source/drains 260 can be formed on thetop surfaces of the vertical fins 121, where the top source/drains 260can be epitaxially grown on the vertical fins. Electrical contacts canbe formed to the gate structures and source/drains to form verticaltransport fin field effect transistors (VT FinFETs).

FIG. 15 is a cross-sectional side view showing shared gate structuresformed on the vertical fins and a bottom spacer without a dielectricseparator on the insulating plug, in accordance with an embodiment ofthe present invention.

In another embodiment, the dielectric separator can be removed using aselective, directional etch, before the gate structures are formed. Thegate dielectric layer 220 can be formed on the exposed surfaces of theinsulating cap 197 and insulating plug 190 which can include thepinch-off void 195. A work function layer can be formed on the gatedielectric layer 220. A conductive gate fill can be formed on the gatedielectric layer 220 or optional work function layer, and form the gatestructure on two adjacent vertical fins 121 without the interposingdielectric separator 200.

FIG. 16 is a cross-sectional side view showing a top spacer on the gatestructures without a dielectric separator, and top source/drains on thevertical fins, in accordance with an embodiment of the presentinvention.

A top spacer 240 can be formed on the gate structures and the verticalfins 121, and an ILD layer 250 can be formed on the top spacer layer240. Top source/drains 260 can be formed on the top surfaces of thevertical fins 121.

In various embodiments, a dielectric separator 200 may be between apredetermined subset of vertical fins 121, whereas a gate structure maybe shared by a different subset of vertical fins 121.

It will also be understood that when an element such as a layer, regionor substrate is referred to as being “on” or “over” another element, itcan be directly on the other element or intervening elements can also bepresent. In contrast, when an element is referred to as being “directlyon” or “directly over” another element, there are no interveningelements present. It will also be understood that when an element isreferred to as being “connected” or “coupled” to another element, it canbe directly connected or coupled to the other element or interveningelements can be present. In contrast, when an element is referred to asbeing “directly connected” or “directly coupled” to another element,there are no intervening elements present.

The present embodiments can include a design for an integrated circuitchip, which can be created in a graphical computer programming language,and stored in a computer storage medium (such as a disk, tape, physicalhard drive, or virtual hard drive such as in a storage access network).If the designer does not fabricate chips or the photolithographic masksused to fabricate chips, the designer can transmit the resulting designby physical means (e.g., by providing a copy of the storage mediumstoring the design) or electronically (e.g., through the Internet) tosuch entities, directly or indirectly. The stored design is thenconverted into the appropriate format (e.g., GDSII) for the fabricationof photolithographic masks, which typically include multiple copies ofthe chip design in question that are to be formed on a wafer. Thephotolithographic masks are utilized to define areas of the wafer(and/or the layers thereon) to be etched or otherwise processed.

Methods as described herein can be used in the fabrication of integratedcircuit chips. The resulting integrated circuit chips can be distributedby the fabricator in raw wafer form (that is, as a single wafer that hasmultiple unpackaged chips), as a bare die, or in a packaged form. In thelatter case, the chip is mounted in a single chip package (such as aplastic carrier, with leads that are affixed to a motherboard or otherhigher level carrier) or in a multichip package (such as a ceramiccarrier that has either or both surface interconnections or buriedinterconnections). In any case, the chip is then integrated with otherchips, discrete circuit elements, and/or other signal processing devicesas part of either (a) an intermediate product, such as a motherboard, or(b) an end product. The end product can be any product that includesintegrated circuit chips, ranging from toys and other low-endapplications to advanced computer products having a display, a keyboardor other input device, and a central processor.

It should also be understood that material compounds will be describedin terms of listed elements, e.g., SiGe. These compounds includedifferent proportions of the elements within the compound, e.g., SiGeincludes Si_(x)Ge_(1-x) where x is less than or equal to 1, etc. Inaddition, other elements can be included in the compound and stillfunction in accordance with the present principles. The compounds withadditional elements will be referred to herein as alloys.

Reference in the specification to “one embodiment” or “an embodiment”,as well as other variations thereof, means that a particular feature,structure, characteristic, and so forth described in connection with theembodiment is included in at least one embodiment. Thus, the appearancesof the phrase “in one embodiment” or “in an embodiment”, as well anyother variations, appearing in various places throughout thespecification are not necessarily all referring to the same embodiment.

It is to be appreciated that the use of any of the following “/”,“and/or”, and “at least one of”, for example, in the cases of “A/B”, “Aand/or B” and “at least one of A and B”, is intended to encompass theselection of the first listed option (A) only, or the selection of thesecond listed option (B) only, or the selection of both options (A andB). As a further example, in the cases of “A, B, and/or C” and “at leastone of A, B, and C”, such phrasing is intended to encompass theselection of the first listed option (A) only, or the selection of thesecond listed option (B) only, or the selection of the third listedoption (C) only, or the selection of the first and the second listedoptions (A and B) only, or the selection of the first and third listedoptions (A and C) only, or the selection of the second and third listedoptions (B and C) only, or the selection of all three options (A and Band C). This can be extended, as readily apparent by one of ordinaryskill in this and related arts, for as many items listed.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a,” “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises,” “comprising,” “includes” and/or “including,” when usedherein, specify the presence of stated features, integers, steps,operations, elements and/or components, but do not preclude the presenceor addition of one or more other features, integers, steps, operations,elements, components and/or groups thereof.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper,” and the like, can be used herein for ease of description todescribe one element's or feature's relationship to another element(s)or feature(s) as illustrated in the FIGS. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the FIGS. For example, if the device in theFIGS. is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the term “below” can encompass both an orientation ofabove and below. The device can be otherwise oriented (rotated 90degrees or at other orientations), and the spatially relativedescriptors used herein can be interpreted accordingly. In addition, itwill also be understood that when a layer is referred to as being“between” two layers, it can be the only layer between the two layers,or one or more intervening layers can also be present.

It will be understood that, although the terms first, second, etc. canbe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another element. Thus, a first element discussed belowcould be termed a second element without departing from the scope of thepresent concept.

Having described preferred embodiments of a system and method (which areintended to be illustrative and not limiting), it is noted thatmodifications and variations can be made by persons skilled in the artin light of the above teachings. It is therefore to be understood thatchanges may be made in the particular embodiments disclosed which arewithin the scope of the invention as outlined by the appended claims.Having thus described aspects of the invention, with the details andparticularity required by the patent laws, what is claimed and desiredprotected by Letters Patent is set forth in the appended claims.

What is claimed is:
 1. A method of forming a vertical transport finfield effect transistor with self-aligned dielectric separators,comprising: foil ling two vertical fins on a bottom source/drain region;forming an isolation channel through the bottom source/drain region intoa substrate between the two vertical fins; and forming an insulatingplug in the isolation channel, wherein the insulating plug has apinch-off void within the isolation channel that does not extend beyondthe bottom source/drain region and the substrate, and a section of theinsulating plug extends beyond the bottom source/drain region and thesubstrate.
 2. The method of claim 1, wherein the insulating plug isformed by a non-conformal deposition process.
 3. The method of claim 2,wherein the non-conformal deposition process is chemical vapordeposition or plasma enhanced chemical vapor deposition.
 4. The methodof claim 1, further comprising forming a dielectric separator on theinsulating plug.
 5. The method of claim 4, further comprising removing aportion of the section of the insulating plug extending beyond thebottom source/drain region and substrate to form an insulating cap incontact with the dielectric separator.
 6. The method of claim 5, furthercomprising forming a gate structure between the dielectric separator andat least one of the two vertical fins.
 7. The method of claim 6, whereinthe two vertical fins are separated by a fin pitch in the range of about15 nm to about 50 nm.
 8. The method of claim 7, wherein the dielectricseparator has a width in the range of about 5 nm to about 40 nm.
 9. Themethod of claim 8, wherein the dielectric separator is a silicon oxide,a low-k dielectric, or a combination thereof.
 10. A method of forming avertical transport fin field effect transistor with self-aligneddielectric separators, comprising: forming at least two vertical fins ona substrate; forming an isolation channel in the substrate between twoof the at least two vertical fins; forming an insulating plug in theisolation channel and along the sidewalls of the at least two verticalfins, wherein the insulating plug has a pinch-off void within theisolation channel; forming a dielectric separator on the insulatingplug; and removing a portion of the insulating plug along the sidewallsof the at least two vertical fins in contact with the dielectricseparator to form an insulating cap.
 11. The method of claim 10, whereinthe insulating plug is silicon oxide.
 12. The method of claim 10,further comprising forming a protective spacer on the two of the atleast two vertical fins, wherein the insulating plug and the protectivespacer are the same material.
 13. The method of claim 10, furthercomprising, forming a bottom spacer on the substrate, and a gatedielectric layer on the bottom spacer, the two of the at least twovertical fins, and the dielectric separator.
 14. The method of claim 13,wherein the pinch-off void within the isolation channel reduces thedielectric constant of the insulating plug.
 15. A vertical transport finfield effect transistor with self-aligned dielectric separators,comprising: two vertical fins on a substrate; an isolation channel inthe substrate between the two vertical fins; an insulating plug in theisolation channel, wherein the insulating plug has a pinch-off voidwithin the isolation channel that does not extend beyond the bottomsource/drain region and the substrate; and a dielectric separator on theinsulating plug.
 16. The vertical transport fin field effect transistorof claim 15, wherein the pinch-off void within the isolation channelforms an airgap that reduces the dielectric constant of the insulatingplug.
 17. The vertical transport fin field effect transistor of claim15, wherein the two vertical fins are separated by a fin pitch in therange of about 15 nm to about 50 nm.
 18. The vertical transport finfield effect transistor of claim 17, wherein the insulating plug issilicon oxide.
 19. The vertical transport fin field effect transistor ofclaim 18, wherein the dielectric separator has a width in the range ofabout 5 nm to about 40 nm.
 20. The vertical transport fin field effecttransistor of claim 19, further comprising a gate dielectric layer onthe two vertical fins and the dielectric separator, and topsource/drains on the two vertical fins.